In recent years, research and development for applying a hologram technology to optical devices and the like are actively performed. Types of the hologram include an emboss type in which interference fringes are recorded as irregularities on a material surface and a volume type in which interference fringes are recorded as refractive index distribution or transmittance distribution.
As a recording material for a volume hologram, a photosensitive composition called a photopolymerization type photopolymer is used (see Patent Literature 1 and Patent Literature 2). In the hologram formation using this photosensitive composition, refractive index distribution corresponding to interference fringes (light and dark) is recorded utilizing the fact that a refractive index difference occurs due to photopolymerization and movement of a monomer accompanying the photopolymerization.